This Tech Note highlights a new photo guide for aging feral 

swine by looking at their teeth. The guide includes 

representative photos of age intervals and descriptions to 

help identify specific teeth as eruption and replacement 

occurs.

Determining the age structure of a feral swine provides insight 

into the population's biological fitness and ecological wellbeing. This knowledge is beneficial for planning control 

strategies or evaluating the success of removal efforts. It is 

also important in disease surveillance and population 

modeling.

Quick Start

Feral swine can be categorized by nine age intervals that are 

defined by the eruption and/or replacement of specific teeth 

from birth to three years of age (See table on page 2). 

The accompanying photo guide provides more details for 

aging feral swine, however to get a quick start, follow the 

directions below.

To protect against infectious diseases, wear appropriate 

personal protective equipment (i.e., gloves, goggles/glasses, 

long sleeved-shirt and pants) when handling feral swine.

1) With the animal anesthetized or euthanized, open the

mouth and look for the canines. A permanent canine is

unmistakable. It is the most notable tooth since it is longer

and larger that the other teeth.

2) If the canine is permanent, work your way forward through

the photo guide starting at Age Interval 4 (30 to 51

weeks). If the canine is deciduous, check for the presence

of the erupting or permanent I3.

Tech Note

April 2018

Aging Feral Swine in the Field

The age of feral 

swine can be 

determined by 

inspecting the 

eruption and/or 

replacement of 

specific teeth.

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• Most age intervals have multiple defining

characteristics, however, only one needs to be present

to confirm the age interval.

• Read the "Special Notes" section of each age interval

as they describe important details to help in identifying

age intervals.

• Check the "Additional Information" section on the back

of the photo guide for illustrations of permanent and

deciduous teeth.

Helpful Tips

If neither the permanent canine nor the I3 teeth are present, 

work your way backwards through the photo guide starting 

at Age Interval 3 (20 to 30 weeks).
Other Aging Techniques

Other aging techniques for feral swine and wild pigs are 

generally limited to laboratory analysis and are not suitable 

for use in the field. Cementum analysis has been explored 

extensively, but environmental factors, such as diet and 

climatic differences, influence the presence and regular 

accumulation of cementum rings. Other techniques include 

evaluating the spina ristae ficilais relative to the upper M3, 

measuring pulp cavity ratios, and morphological 

measurements. Several techniques to age older animals by 

visually observing molar wear or measuring molar dentin 

have been developed and used with some success.

Note: The accompanying photo guide is based on efforts by 

former USDA employee George Matschke. Matschke 

monitored the timing of tooth eruption and replacement of 

captive-raised offspring of wild caught Eurasian wild boar.

(Matschke, G.H. 1967. Aging European wild hogs by 

dentition. Journal of Wildlife Management 31:109-113)

Additional Information

For more information on aging feral swine, 

please contact:

USDA-APHIS-Wildlife Services 

National Wildlife Research Center 

4101 LaPorte Avenue

Fort Collins, CO 80521

(970) 266–6000

United States Department of Agriculture

Animal and Plant Health Inspection Service

The U.S. Department of Agriculture (USDA) is an equal opportunity provider and employer. 

Disclaimer

It is well documented that tooth eruption and replacement 

in domestic pigs occurs earlier than wild boar. Feral swine 

have been in the continental U.S. since the 1500s and 

introductions of Eurasian wild boar began in the late 1800s. 

The origin of ancestry and unknown degree of hybridization 

between domestic and European lineages may result in 

differences in the timing of tooth eruption and replacement 

in some feral swine encountered in the U.S. 
(Upper left) P1s are absent on 

the lower jaw. M1 is fully 

erupted. Note the 3 cusps on 

the lower p4. The p2, p3, and 

p4 have little wear. The canines 

and i3s are deciduous.

(Lower left) P1s are present on the upper 

jaw. M1s are intact. The canines, p2, p3, 

and p4 show little visible wear. 

(Right) P1 is intact on the left and erupting 

on the right. All other teeth are deciduous 

except the M1. Note the broken i2.

(Left) Note the 

deciduous canines, 

erupting I3s, and 

only one P1. All 3 

cusps of the p4 

show wear.

4: 30-51 weeks

Defining Characteristics:

 C intact or erupting AND/OR

I3 intact or erupting

Special Notes:

i1s, i2s, p2, p3, and p4s are deciduous. In this 

age interval, the permanent canines and I3s 

both begin to erupt and replace the deciduous 

teeth at roughly the same time. M1s are present; however, if M2s are erupting, the animal 

should be assigned to Age Interval 5 (12-18 

months).

(Upper left) One i3 is 

absent. It likely fell 

out. Note the early 

eruption of the 

permanent canines. 

The p2, p3, and p4s 

have moderate wear 

and dentin present.

(Lower left) Note 

the lower I3 and the 

upper i3. The lower 

canine is still 

deciduous and the 

upper canine was 

recently lost. 

TIP:

Use your finger 

to wiggle the 

incisors to 

confirm if 

deciduous or 

permanent. 

Deciduous teeth 

have shallow 

roots and will be 

loose just before 

replacement.

1: 0-8 weeks

Defining Characteristics:

 i2 and p2 absent

Special Notes:

All teeth are deciduous. 

Deciduous i3 and canine 

present at birth. i1, p3, and 

p4 erupt within 2-3 weeks.

Feral Swine Aging Guide 

Overview

This guide uses tooth eruption and replacement to estimate the age of feral 

swine. Each age interval is defined by the presence or absence of specific 

teeth. For most teeth, the entire time range of possible eruption and/or

replacement is included within one age interval. However, some overlap 

between age intervals may exist. When estimating age, start by checking 

the canines. If permanent, start at Age Interval 4 and work forward through 

the guide. If deciduous and Incisor 3 is absent, start at Age Interval 3 and 

work backwards through the guide. Capital and lowercase letters depict 

permanent and deciduous teeth, respectively (I—Incisor, C—Canine, P—

Premolar, M—Molar). See “Additional Information” on the back of the guide 

for illustrations of permanent and deciduous teeth. 

2: 8-20 weeks

Defining Characteristics:

 i2 intact or erupting AND/OR

p2 intact or erupting

Special Notes:

All teeth are deciduous. The i1, i3, canine, p3, 

and p4 (3 cusps) are present, but the i2 and p2s 

do not erupt until 8-20 weeks. Many, but not all, 

feral swine up to 20 weeks old will have striped 

pelage. This will dissipate sometime between 16-

24 weeks of age as individuals begin to take on 

adult coloration (Mayer 1991).

Authors’ Note

The data used to identify age intervals in this guide originate from Dr. George Matschke’s 1967 publication Aging European wild hogs by dentition. Matschke recorded 

the timing of tooth eruption in captive-raised offspring of wild caught Eurasian boar in Tennessee. It is the only data on feral swine tooth eruption and replacement 

collected from live feral swine in the U.S. Most wild boar data from other countries tend to correlate well with Matschke’s findings with only minor differences. Age

Interval 8, suggesting complete dentition between 36 and 48 months, was derived using data from multiple studies including Matschke (1967), Boitani and Mattei

(1992), Clark et al. (1992), and Iff (1978). It is the authors’ conclusion that Age Interval 8 captures most feral swine with fully erupted, complete dentition. However, it is 

well documented that domestic pigs erupt and replace teeth earlier than wild boar. The origin of ancestry and unknown degree of hybridization between domestic and 

European lineages may result in differences in the timing of tooth eruption and replacement in some feral swine encountered in the U.S. 

Citations

Boitani, L. and L. Mattei. 1992. Aging wild boar (Sus scrofa) by tooth eruption. In F. Spitz, G. Janeau, G. Gonzalez, and S. Aulagnier (eds.), Ongules/Ungulates 91 Proceedings of the international symposium. Toulouse, France, 

September 2-6, (1991), Société Francaise pour l'Etude et la Protection des Mammifères, and Toulose: Institut de Recherché sur les Grands Mammifères, Paris & Toulouse, France. 661 pp. : 419-421.

Clarke, C.M.H., R.M. Dzieciolowski, D. Batcheler and C.M. Frampton. 1992. A comparison of tooth eruption and wear and dental cementum techniques in age determination of New Zealand feral pigs. Wildlife Research (6):769-778. 

Iff, U. 1978. Determination de lage chez le Sanglier. Diana 95(10):377-381.

Iff, U. 1983. Alterbestimmung und Schatzung biem Schwarzwild (Age determination and estimation in wild boar). Wild und Hund, 86(11):26-30.

Matschke, G.H. 1967. Aging European hogs by dentition. Journal of Wildlife Management 31:109-113.

Mayer, J.J. 2002. A simple field technique for age determination of adult wild pigs: Environmental information document. WSRC-RP-2002-00635. Westinghouse Savannah River Company, Aiken, South Carolina.

Mayer, J.J. and I.L. Brisbin, Jr. 1991. Wild pigs in the United States: Their history, comparative morphology, and current status. The University of Georgia Press, Athens, Georgia.

Joseph Halseth, Michael Lavelle, Nathan Snow and Kurt Vercauteren  USDA Wildlife Services, National Wildlife Research Center

(Upper left) Note the 

recently erupted upper i2. 

This tooth is light in color 

and has well defined tips. 

The lower i2 is intact (fully 

erupted).

(Lower left) This same 

individual as above 

has intact p2s, but 

does not have P1s or 

M1s indicative of the 

next age interval. 

(Above) This 7-week piglet has i1s, canines, and i3s (top 

i3 is missing), as well as p3 and p4s. Note the absence of 

i2s and p2s and the presence of a lower, 3-cusped p4.

(Above) The upper i2 is just beginning to erupt and 

the upper p2 is intact. Note the light color and 

minimal staining on the p2.

3: 20-30 weeks

Defining Characteristics:

 P1 intact or erupting AND/OR

M1 intact or erupting

Special Notes:

M1s and P1s do not exist as deciduous teeth. One 

or both lower P1s may be absent. The lower P1s

are well spaced between the canine and p2. The 

upper P1s are grouped with the other premolars. 

The presence of M1s often define this age 

interval.

p2
(Left) Note missing Canine and M1; significant 

wear on M2s and M3s. I3s are missing. (Above) P2 

and lower M3 is worn to the gum and M1 is 

missing. (Right) Note dentin on P4, M1, M2, and 

M3s, as well as cupping/sharp edges from occlusal 

wear on the M3s.

6: 18-26 months

Defining Characteristics:

 I2 intact or erupting AND/OR

Lower M3 intact or erupting

Special Notes:

The lower I2 will generally erupt (18-22 months) 

before the upper I2 (21-26 months). The lower M3 

will erupt between 22-26 months. If a lower M3 is 

present, check for the upper M3. If the upper M3 is 

erupting or intact the animal should be assigned to 

the next age interval (7: 26-36 months). The M3s

(not present as deciduous teeth) have 2 cusp pairs

and a final large single cusp.

(Left) Note the upper and lower 

I2s. (Above) The recently lost i2 

is being replaced by the I2. 

(Upper right) The second cusp 

pair is erupting and the final 

single cusp is not yet present in 

the lower M3.

7: 26-36 months

Defining Characteristics:

 Upper M3 erupting

Special Notes:

The upper M3 erupts on average 4 months after the 

lower M3. If the upper M3 is intact, the animal 

should be assigned to Age Interval 8.

8: 36- ~48 months

Dentition complete with intact M3s. Some wear 

may exist on the lower M3s. Look for fully exposed 

single cusp on the rear of upper M3. The lower M3 

has 2 cusp pairs and a single rear cusp.

9: Older Adults ~48+

Defining Characteristics:

 Visible wear on M3s

 All other teeth show visible wear and some

teeth may be missing

Special Notes:

Pay attention to plaque and tarter build up, 

discoloration, and decay as evidence of older teeth. 

Dentin will be present on worn surfaces of teeth 

and some tooth cusps will be worn down. Observe 

the level of tooth wear decreasing towards the 

gum line.

5: 12-18 months

Defining Characteristics:

 M2s intact or erupting AND/OR

I1s intact or erupting AND/OR

P2s, P3s, P4s intact or erupting

Special Notes:

The i2 is still present. The M2s (not present as 

deciduous teeth) and I1s erupt earlier in this age

interval than P2s, P3s, and P4s. The P4s have 2 

cusps rather than 3 cusps like the p4. The I1s can 

be tricky to identify. They are generally a little 

bigger, lighter in color when new, and have more 

defined tips than the worn i1s.

(Upper left) Note partially erupted M2.

(Lower left) Note newly replaced P2, P3, 

and P4s with light color and 2 cusps on 

the P4. The M2 is discolored from use. 

(Upper right) Note wear on p3 and p4 

and erupting M2. 

(Center left) Note newly erupted I1s with lighter color and defined tips. 

(Center right) The right I1 is in the process of replacing the i1. The 

canines are permanent.

(Below left) A modified illustration from Iff (1983) showing permanent dentition from German wild boar.

(Below right) Illustration of deciduous dentition from Matschke (1967). 

Additional Information 

A detailed method for estimating feral 

swine age over 48 months using tooth 

wear is available in Mayer (2002) (See 

“Citations” on front page).

More detailed illustrations of tooth 

eruption and replacement on the lower 

mandible is available in Iff (1983) 

(See “Citations” on front page).

(Lower right) The single rear cusp on the lower M3 

is erupting. It will eventually be above the gum line.

(Left) Only the first cusp pair has erupted on the 

upper M3. Note minimal wear on M1 and M2

(Lower left and right) Intact dentition with minimal 

wear on the M3s. Note the 2 pairs of cusps and a 

single rear cusp on both of the M3s. Note rear cusps 

of M3s are above the gums. There is also wear and 

dentin on M1s and M2s. These individuals are 36 to 

48 months old.